# Plato's chemical formula for water

In a paper about Plato's Timaeus I came across a cryptic note saying: "Academic research usually avoids noting that Plato's assertion about water consisting of two parts air and one part fire is strikingly similar to the modern chemical formula (H2O)." Most obviously this refers to the text found at the end of 56d:

water.. is capable of becoming a compound of one corpuscle of fire with two of air

The Timaeus famously linked the the four elements with regular solids, water being the icosahedron (20 faces), air - the octahedron (8), fire - the tetrahedron (4), so the count is good: $20= 2\times8 +4$. The modern formula for water H2O has been established early in the 19th century. Who was the first to note this coincidence and what later comments are there?

• Plato's triangle "chemistry" also implies that two corpuscles of fire form one of air, and five form one of water, as do one air and three fires. Given the number of ways one can do numerology on Platonic solids, I am not sure the coincidence is that "striking" to be noted and commented on. See Lloyd's Chemistry of Platonic Triangles for details. – Conifold Jun 13 '17 at 2:00
• "Academic research" as opposed to what? Mysticism? – fdb Jun 15 '17 at 22:24
• I always read the Timaeus as a type of laughing at physicists. Something like: If your understanding of physics takes you away from a teleological understanding of the cosmos then your physics is immoral. Stop focusing on the physical world and return to mental realm. To read Plato as an actual attempt at understanding the cosmos I think undermines his political and moral philosophy. But also that's just my reading... – Mason May 12 '18 at 17:15
• No. It's not "just my reading," this is my interpretation after listening to Dr. Sugrue's lectures on the Platonic Dialogue in the Great Courses Series: Plato, Socrates, and the Dialogues . thegreatcourses.com/courses/… – Mason May 12 '18 at 17:20
• Re_Mason: Just as his peers, the sophists and rhetoricians, Plato was interested in arguing. Re_fdb: Yes, that's it, outside Atlantis and its fans. Re_Cornifold: 2x8+4=8+3x4=5x4 the last is simply "burning"; so perhaps entropy grows from 1x20 to 20x1, doesn't it? – sand1 May 14 '18 at 9:10